The dossier file parser component we use to get battle data seems to have some problems reading data from WoT 9.12.
Hopefully an update will be available later this evning (Nov 18th), and we will release a patch as soon as we get it.
After a battle an error message might appear (example below from the log file), or you might be lucky and get no error and the battle might seem to be recorded. You will most likly get a lot of strange values, and the ratings (WN7, WN8 and EFF) will be calculated wrong.
When we are able to fix the problem we will schedule a "forced" update on all data on startup to get correct data. Recorded battles with incorrect values should better be deleted (right click on the row in the battle view) to avoid incorrect average and total values.